The invention relates to a new and improved waste disposal system for recreational vehicles and the like, and is primarily directed to a sanitation system for marine craft.
Waste disposal has long been a problem for the owners of boats and other types of recreational vehicles. In most places, the indiscriminate dumping of raw or untreated waste material is prohibited by environmental regulations. Accordingly, a variety of different waste disposal systems have been previously proposed. For example, chemical treatment systems treat waste material with chemicals to destroy the bacterial content. Generally, they employ a treatment tank into which the waste material from a water closet or head is placed. Chemicals are added to the treatment tank and allowed to interact with the waste material for a sufficient time to kill the bacteria. Many such systems employ macerators to chop or break up the waste material into small particles and to mix the waste material with the chemical solution in the tank to enhance chemical action. After a sufficient period of time for the bacteria to be killed or reduced to an acceptable level, the contents of the tank are discharged into the environment. Typical of such systems are those disclosed in Belden, U.S. Pat. No. 3,044,077 of July 17, 1962, and Russo, U.S. Pat. No. 3,762,553 of Oct. 2, 1973.
Chemical systems have a number of disadvantages. The chemicals which they employ are expensive and produce a strong unpleasant odor. Moreover, they are not always totally effective in killing bacteria, so that the discharged waste material may still cause pollution and environmental problems.
Another type of waste disposal system incinerates the waste material. Such systems typically employ a macerator unit to convert the waste material in a holding tank to a liquefied effluent. The liquefied waste material is then pumped to an incinerator unit where it is burned. Alternatively, the liquefied waste material may be fed in controlled amounts directly into the hot exhaust of an internal combustion engine where it is sterilized through calcination. Such systems are generally rather complex, requiring a complicated metering system to control the amount of liquefied waste material pumped from the tank to the incinerator or to the engine exhaust. Systems utilizing the heat of an engine exhaust to incinerate the waste material tend to be limited in the amount of waste which can be handled. Furthermore, such systems are not practical on sailboats. Typical of these systems ae those disclosed in Sturtevant, U.S. Pat. No. 3,936,888 of Feb. 10, 1976, and Dallen, et al, U.S. Pat. No. 4,161,792 of July 24, 1979.
Increasingly strict Federal and State environmental regulations prohibit the discharge of even treated waste material in certain areas, such as inland waterways and lakes. Chemical and incinerator type waste disposal systems cannot be used in these areas. For boat owners, this means that waste material must be retained on-board in a holding tank. Shore-based pump-out facilities are necessary to collect the waste material from boats. However, very few marine pump-out facilities exist to accommodate boats requiring waste disposal services. Those that do exist commonly have a single pump-out station at a fixed location. This requires that the boat owner bring his boat to that particular point in a marina, for example, to have his holding tank pumped out. This is not only inconvenient, but it is also expensive.
Typically, the holding tanks on small boats have limited capacities, e.g., 20 to 30 gallons, and must be pumped out frequently. Moreover, holding tanks on boats generally do not have any means for monitoring the level of waste material in the tank. A boat owner, rather than risk the chance of an overflow, desires to discharge his holding tank frequently. The expense and inconvenience of having to take his boat to a pump-out station are an incentive for him to disregard the regulations and surreptitiously discharge the holding tank directly into the water, frustrating the purposes of the environmental regulations.